Category: Outer Space

The explorers of outer space – beyond the ionosphere – are the astronomers. With intellect and imagination they have reached out millions of miles and brought down the knowledge on which our understanding of the universe is based.

About time

One of the immediately practical uses of astronomy is the accurate determination of time. Today we can measure it to a thousandth of a second but we still use the motions of heavenly bodies as our primary standard. This subject, particularly as it bears upon life and work today, forms the first sequence of displays on the Outer Space gallery. Its entrance can be recognised from all over the Dome by a replica of the famous Greenwich Time Ball, which used to give a time check at one o’clock every day so that ships in the Thames could regulate their chronometers.

Modern knowledge of the heavens is an international achievement in which British astronomers have played a great part. Most of the displays that follow on this gallery, giving vivid impressions of various parts of the universe, are based, therefore, on knowledge contributed by a number of nations.

The planets

They begin with our own earth – presented, not as we know it from first-hand experience, but as one of a number of heavenly bodies with its own peculiar way of behaving in space. Next we show the major planets – Mars, Jupiter, Saturn and Uranus, as they might be seen from their satellites. Into this series of displays comes our own satellite, the moon, whose surface we know much more intimately than that of any of the planets. Amateur astronomers have added a lot to this knowledge, in determining the depth of the various craters, estimating the changing surface temperatures and mapping its features.

The stars

Beyond the solar system, which is illustrated in moving model form, we have to go vast distances in our imaginations before reaching other bodies. Our own solar system is merely a tiny entity in the galaxy we call the Milky Way. Outside the Milky Way are many other vast clouds of stars – the nebulae. At such distances we can only see stars, any planets they may have around them are unknown to us.

Our own sun is, in many ways, a typical star, and by studying it in detail astronomers have come to learn much about stars in general. Following on this, brilliant reasoning by physicists and astronomers (many of them British) has given us knowledge of the life history of a star. We present this by a new visual technique in the Outer Space gallery.

Telescopes

Of all discoverers, Isaac Newton must surely be rated the worlds greatest. Some of his achievements are shown in the “Physical World” section of the Dome. But his fertile mind contributed a great deal also to astronomy. It was he who showed that the physical universe is governed by law and not by caprice. In addition, he designed the first reflecting telescope, invented the calculus and laid the foundations of spectroscopy – all tools of the astronomer.

Since Newton, Britain has continued to be very active in designing telescopes and the gear associated with them. As modern examples we show a replica of the new St. Andrews telescope and, on the ground floor, the 74-inch telescope now being completed for use in Australia. But bigger and better though our telescopes become, it is now believed that a point will be reached in space beyond which they will never be able to penetrate, because the universe is expanding at a speed greater than that of light.

The radio telescope

The latest tool of astronomers is radio. A few years ago it was discovered that short-wave radio signals came to us from outer space. It is now known that these originate in part of the sky where there are no visible stars. How they arise is still a mystery. When we solve it, we shall know more about the origin of cosmic rays. You can see in this section what these signals look like.

But as well as using radio passively, as it were, by studying signals originating in outer space, we can also employ it actively for astronomical exploration. This is one of the newer uses of radar, which, in short, enables us to see by means of radio waves. Strong pulses are sent out from the earth and received again after reflection from heavenly bodies. By this technique we can locate meteors, for example, even when they are invisible to the eye, and calculate their velocity accurately.

The main display of this new method is the radio telescope which visitors themselves will be able to operate. Its aerial is on top of the Shot Tower and can be beamed on to the moon. The signals transmitted take about two and a half seconds to get to the moon and be reflected back to earth. Visitors will be able to see them clearly on a cathode ray tube.

This radio telescope is an advance on equipment yet produced because it can reach the moon whenever it is above the horizon. Other transmitters have only obtained echoes when the moon was near the horizon – rising or setting. The radio telescope will be used solely for scientific purposes after the Exhibition closes, and even while it is open it will be contributing to contemporary research on problems of fading. It is hoped that this will start by giving us more information about conditions in the upper atmosphere of the Earth and on the surface of the moon.